Apparatus and method for liquid introduction in oil wells



United States Patent [56] References Cited UNITED STATES PATENTS [72]lnventor CharlesJ.Engle Bartlesville, Okla. [21] AppLNo. 807,745

8/1968 Littleetal. 3,414,057 l2/l968 Harbison.................

O m m .mmm ZvB 057 555 999 111 Ill 1131 1 1 398 77 042 30 222 [22] FiledMar. 17, 1969 [45] Patented Dec. 22, 1970 [73] Assignee PhillipsPetroleum Company a corporation of Delaware Primary Examiner-Marvin A.Champion Assistant Examiner-Ian A. Calvert Attorney-Young and QuiggABSTRACT: Chemical treatment of oil wells is effected by placing theparticular chemical in the well bore at the desired depth by the use ofsubsurface apparatus comprising a hollow sucker rod, the core of whichis in communication with the well bore through the production tubing.The communication ports are isolated by packing means from the producedfluid flowing upwardly through the production tubing. The produced fluidbypasses the packed off area of the production tubing through a suitablecrossover flow device.

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EOW M Mn m ww M Ans PR PM Amoo U mm M H UN 5 H mm PATENT ED 115x122 I970INVENTOR. C. J. ENGLE 7 7 9? A T TORNEVS APPARATUS AND METHOD FOR LIQUIDINTRODUCTION IN OIL WELLS This invention relates to a method andapparatus for introducing a liquid into an oil well through a hollowsucker rod.

The introducing of various liquids into oil wells in order to increaseproduction is known in the art. Accordingly, modern productiontechnology recognizes the value of introducing defoaming agents,slurries, fluid cements, water for water flooding, combustion supportinggas for tire flooding, and the like. The production of foam in the wellrequires the introduction of a defoaming agent because the oil wellpumping apparatus relies for operability on the incompressibility of theproduced crude. Thus, when foam exists in the crude, the incompressiblenature of the produced stream is partly or wholly destroyed and thedownhole recovery pump either functions at greatly reduced efficiency orcompletely fails to raise the produced stream to the uphole location.

The reason foam exists in the produced crude is unknown; however, onetheory suggests that foaming occurs as a result of the release of CO,and other dissolved gases as the pressure on the crude drops fromformation pressure to bottom hole pressure.

To a certain extent all reservoirs contain dissolved gases and foamingcan become a significant production-problem in any reservoir andparticularly in reservoirs that-have been subjected to an in situcombustion secondary recovery technique.

According to one typical type of insitu combustion operation a hightemperature zone is established in the oil-bearing region of a reservoiraround a well bore. Suitable heating means for'establishing a hightemperature zone within the formation can comprise an electrical heatingdevice or a gas fired bottom hole igniter or heater. Upon introducing acom bustion-supporting or an oxygen-containing gas such as air into theheated formation via the well bore a high temperature combustionzone'i's created by the reaction between the oxygen and combustibleresidues within the high temperature zone of the oil-bearing regions.Upon continued introduction of the combustion-supporting gas this hightemperature zone will commence to move into the formation outwardly fromthe well bore.

The combustion products of the combustion are primarily CO and H andatthe elevated pressures existing in subterranean reservoirs much of thelarge volume of CO is dissolved in the crude and subsequently releasedwhen the pressure on the crude drops to downhole pressure duringrecovery. Thus, foaming is even a greater problem in reservoirssubjected to in situ combustion andin the case of low gravity, viscouscrudes that produce a very stable foam, such as the'Morichal crudes fromVenezuela and certain of those'in the United States, the problem becomesacute.

Since the foam is thought to be produced in the oil bearing region ofthe well when the pressure .on the crude is reduced, a problem exists inplacing the defoamingagent in the precise location where the foam isproduced. If the defoaming agent is merely poured in the top of thewell, it can become flocculated by the action of the upcoming producedgas and consequently fail to function. Even if the defoamer reaches thedownhole location, it can form a layer on top of the column of crude inthe well and fails to function because it is on top of the columninstead of farther down into the column where the crude flows out offormation and into the bore hole and produces foam.

Thus, this invention represents an improvement over the prior art inthat a liquid, and in a preferred embodiment a defoaming agent, can beintroduced into the oil bearing region of a producing well through ahollow sucker rod and in another embodiment can be introduced into theregion where the crude flows out of the formation and into the borehole.

In one embodiment of .this invention, an apparatus is provided forintroducing a liquid into the oil bearing region of a producing casedwell comprising a hollow sucker rod with a passageway from the exteriorto the hollow region. In another embodiment of this invention, a lengthoftube is positioned in a casedwell, a reciprocating pumping-means ispositioned within the oil bearing region of the cased well and .a hollowsucker rod is operably attached to the reciprocal pumping means. Firstand second packing means are positioned respectively uphole and downholefrom said sucker rod passageway slidably sealing said sucker rod to saidtubing and thus forming an annular chamber. Additionally, means areprovided to conduct said introduced liquid from the annular chamber tothe oil bearing region, and bypass means are provided so the reciprocalpumping means can pump the produced fluid around the annular chamber andup the annular passageway between the tubing and sucker rod. In onestill further em? bodiment of the invention, a closure is providedbetween the tubing and casing and a means positioned through saidclosure to communicate produced gas upward through the closure. In onestill further embodiment of the invention, a closure means is positioneddownhole from the inlet of the pumping means and the tubing contains apassageway positioned uphole from said closure and downhole from saidpumping inlet. In one additional embodiment the means to conduct theintroduced liquid from the annular passageway to the oil bearing regioncomprises a means to conduct said liquid downhole from said closure andthe introduced liquid comprises a defoaming agent. In one still furtherembodiment of the invention, the means to communicate produced gas upthrough said closure comprises a first tube and the means to conductfluid from said annular chamber to the oil bearing region comprises asecond tube annularly positioned within said first tube.

One object of this invention is to providemethod and apparatus forintroducing liquid into the oil bearing region of an oil well through ahollow sucker rod. Another object of this invention is to prevent theformation of foam within the oil hearing region of a producing well.Another object of this invention is to introduce a defoaming agentdirectly into the oil bearing region of a producing well. Other objects,advantages and features of this invention will be readily apparent tothose skilled in the art from the following description, drawings, andappended claims.

The attached FIG. represents a portion of a profile view in partialcross section of ,a cased producing well incorporating established bymethods well known in the artpenetrating a subterranean oil bearingformation thus forming an oil bearing region within the bore hole. Thebore hole is then cased by a casing 5 and perforated so as to formpassageways between the oil bearing formation and the bore hole. Thepressure differential between the oil bearing formation and the borehole causes crude to flow from the oil bearing formation throughpassageways l0 and fonn a column of crude in the bore hole. A length oftubing is then positioned within the bore hole. Tubing 20 contains avalve 35, bypass means 25, and a means to conduct an introduced liquidinto the oil bearing region. A hollow sucker rod 36 is then positionedwithin said tubing connected to a pumping cylinder 40 containing a valve45. Tubing 20, valve 35, pumping cylinder 40 and valve cooperate tocomprise a reciprocal pumping means when actuated by sucker rod 36. Thesucker rod 36 contains a passageway from the exterior to the hollowportion of the sucker rod. Sucker rod 36 is slidably sealed forreciprocating movement within said tubing 20 by packing means andpacking means 60, thus forming an annular chamber between the closures.In an additional embodiment, packing means seals tubing 20 within casing5 so as to provide a reservoir below packing means 70 in which thedefoaming agent can be inserted and isolated so as to intimately admixwith the foaming crude. I

Packing means 70 can be located at any distance up or downhole in thecolumn; however,packing means 70 must be equipped with a means tocommunicate produced gas upward through said closure. If the top-ofcolumn 15 is below packing means 70 satisfactory results can beachieved, although in a preferred embodiment packing means '70 is belowthe top of column 15.

from the annular chamber 653a more desirable'result is achieved byincorporating packing means 70 into the inven-.

tion and introducing the liquid downhole from packing means 70 throughliquid introduction means 30. In the preferred embodiment where theliquid is a defoaming agent this places the defoaming agent in theprecise location where the foam is thought to form and greatly increasesthe defoaming action. If packing means 70 is not used satisfactoryresults can still be obtained, particularly when the top of the columnof crude 15 is above the passageway from the annular chamber 65 into thebore hole and perforations extend uphole to the vicinity of the annularchamber.

N In a preferred embodiment of the invention, the packing means 70 ispositioned downhole from inlets 85 through said tube 20. If inlets 85are not provided in tubing 20, a pressure differential is created acrosspacking means 70 because-the gas exiting through means 75 necessarilycarries out quantities of liquid which will accumulate above packingmeans 70 and produce an extremely heavy column of: liquid above packingmeans 70. Althoughthe invention will operate in this manner, it isdesiredto provide passageways 85 so the pressure in the column of crude15 above packing means 70'will be substantially similar to that belowpacking means 70. In a preferred embodiment, the means to conduct theintroduced liquid from the annular chamber to the oil bearing regioncomprises a first tube and the means to communicate produced gas upwardthrough said packing means 70 comprises-an annularly positioned tube 75.

Departing from the structure of the invention and focusing attention onthe operation of the invention, sucker rod 36 is reciprocally driven bysuitable uphole means while cylinder 40 and valve 45 cooperate with tube20 and valve 35 so as to transport crude from the column of crude 15 upthe annular region above cylinder 40 between tubing 20 and sucker rod36.- Subsequently the produced fluid is conducted through bypass means25 and up the annular region between'tube 20 and sucker rod 36 to anuphole location where it is recovered and subjected to furtherprocessing steps. The gas produced by the practice of this inventionflows up the annular region between tubing 20 and casing and isrecovered and processed. In the embodiment where packing means 70 isutilized, the gas that is produced below packing means 70 flows throughmeans 75 and subsequently to the uphole location.

According to the operation of this invention, the liquid, which cancomprise any liquid but in a preferred embodiment comprises a defoamingagent, is injected by suitable means such as described in Reese U.S.Pat. 2,639,674 down the hollow region of sucker rod 36-and flows intoannular chamber 65 while sucker rod 36 is reciprocatingly drivingcylinder 40 that cooperates with tubing 20 and the noted valves tocomprise-a pumping means. The liquid then fiows from annular chamber 65through means 30 into the oil bearing region and in a preferredembodiment where the packing means 70 is used, the liquid is depositeddownhole fro'm packing means 70. Thus, according to the operation of thepreferred embodiment of this invention a defoaming liquid can beintroduced down the hollowsucker rod and further conducted into the oilbearing region to be intimately mixed with the oil flowing into thecased well so as to reduce foaming.

Examples of liquids that can be introduced down hollow sucker rod36include defoaming agents, slurries, fluid cemerits, water for waterflooding, gas for fire flooding. As previously noted in a preferredembodiment, a defoaming agent is introduced. The defoaming agent used inthe preferred embodiment can comprise any material capable of beinginjected in the bore hole according to-this invention that will reduceor eliminate foaming. Specifically, two kinds of silicon compounds arecommercially available to reduce or eliminate foam. One is a compoundedsilicon antifoam and the other is a straight dimethyl oil. Compoundedantifoams'are dispersions of silica filler in a low viscosity siliconfluid. The dimethyl silicon oils are high viscosity long chain polymersof silicon to oxygen bonds with two methyl groups attached to each car-This invention is thus broadly applicable to the introduction of aliquid into the oil bearing region of aiwell through a hollow suckerro'cl. 4

As noted above, the drawing is merely diagrammatic and is not intendedto fully show all component parts of the'eq'uipment which one skilled inthe art would routinely design 'for operation. Specifically as noted,the position of packing means 70 can vary within the length of thecolumn and several embodiments of means 30 and means 75 are provided.Indeed,

the showing of one element of piece of equipment does not mean that allsuch are similar pieces of equipment which may or can be designed by oneskilled in the art in possession of this-disclosure. cannot be utilizedas substitution therefor.

Likewise, the omission of an element which one skilled in the art mayinclude in an actual unit does not mean that such a piece of equipmentis intended to be omitted simply because it does not appear in thedrawing. Sufiice to say the drawing is for illustrative purposes only,as is the description thereof.

1 claim:

1. Apparatus for introducing a liquid into the oil bearingregion of aproducing cased well comprising:

a. a length of tubing residing in said cased well from an upholelocation to said oil bearing region;

b. reciprocal pumping means positioned within said casing in the oilbearing region adapted to pump produced fluid up said tubing;

c. a hollow suckerrod containing a passageway from the exterior of therod to the hollow region, said rod positioned within said tubing andadapted to reciprocally actuate said pumping means;

d. first and second packing means positioned respectively.

up hole and down hole from said sucker rod passageway slidably sealingsaid sucker rod to said tubing so as to form an annular chamber;

e. means to conduct said introduced liquid from said annular chamber tosaid oil bearing region; and

f. bypass means to conduct said produced fluid around said annularchamber and up said tubing.

2. The apparatus of claim 1 further comprising:

a. closure means between said casing and tubing; and

b. means to communicate produced gas upward through said closure.

3. The apparatus of claim 2:

a. wherein said closure means is positioned down hole from the inlet ofsaid pumping means;

b. wherein said tubing contains a passageway positioned up hole 'fromsaid closure means and downhole from said.

tube centrally positioned within said first tube.

5. A method of introducing a liquid into the oil bearing zone of aproducing cased well comprising the steps of:

a. providing a reciprocally driven pump in pumping position in said oilbearing zone;

b. actuating said pump with a hollow sucker rod containing a passagewayfrom the exterior of the rod to said hollow region;

c. providing a tubular closure around said sucker rod;

d. forming an annular chamber by:

chamber to said'oil bearing region comprises a second I 1 providing afirst closure means uphole from said sucker rod passageway slidablysealing said sucker rod to said tubular closure; v

2 providing a second closure means downhole from said sucker rodpassageway slidably sealing said sucker rod to said tubular closure;

e. conducting a liquid down said hollow sucker rod through saidpassageway and annular chamber and into said oil bearing zone;

f. pumping produced fluid from said oil bearing zone around said annularchamber and up said tubular closure to an uphole location; and

g. recovering produced gas from said oil bearing zone.

6. The method of claim 5 further comprising the steps of:

a. providing a closure within said casing;

b. providing a passageway through said casing closure for the recoveryof said produced gas.

7. The method of claim 6:

a. wherein said casing closure is positioned downhole from the inlet ofsaid reciprocally driven pump;

b. wherein said liquid comprises a defoaming agent;

c. wherein said tubular closure contains a passageway positioned upholefrom said casing closure and downhole from said pump inlet. I

8. The method of claim 7 further comprising:

a. recovering produced gas through a tubular passageway in said casingclosure; and v p b. introducing said defoaming agent into said oilbearing zone through a tubular member positioned annularly within saidgas recovery passageway.

